One thing I've noticed is the many anachronisms with weapons. There were no flatop AR's in Vietnam, Colt-made 4X scopes were mounted on carry handles. Also no undermounted grenade launchers in 1961; Colt made the first one, the XM148, in 1964. There also were no ACOG's (1990's) in 1961, nor MP-5K's in 1963 (1976). COD has always been fairly accurate in its weaponology, so these mistakes are a bit disappointing.